clippy_lints/src/unsafe_removed_from_name.rs

   1 use clippy_utils::diagnostics::span_lint;
   2 use rustc_ast::ast::{Item, ItemKind, UseTree, UseTreeKind};
   3 use rustc_lint::{EarlyContext, EarlyLintPass};
   4 use rustc_session::{declare_lint_pass, declare_tool_lint};
   5 use rustc_span::source_map::Span;
   6 use rustc_span::symbol::Ident;
   7
   8 declare_clippy_lint! {
   9     /// ### What it does
  10     /// Checks for imports that remove "unsafe" from an item's
  11     /// name.
  12     ///
  13     /// ### Why is this bad?
  14     /// Renaming makes it less clear which traits and
  15     /// structures are unsafe.
  16     ///
  17     /// ### Example
  18     /// ```rust,ignore
  19     /// use std::cell::{UnsafeCell as TotallySafeCell};
  20     ///
  21     /// extern crate crossbeam;
  22     /// use crossbeam::{spawn_unsafe as spawn};
  23     /// ```
  24     pub UNSAFE_REMOVED_FROM_NAME,
  25     style,
  26     "`unsafe` removed from API names on import"
  27 }
  28
  29 declare_lint_pass!(UnsafeNameRemoval => [UNSAFE_REMOVED_FROM_NAME]);
  30
  31 impl EarlyLintPass for UnsafeNameRemoval {
  32     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
  33         if let ItemKind::Use(ref use_tree) = item.kind {
  34             check_use_tree(use_tree, cx, item.span);
  35         }
  36     }
  37 }
  38
  39 fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext<'_>, span: Span) {
  40     match use_tree.kind {
  41         UseTreeKind::Simple(Some(new_name), ..) => {
  42             let old_name = use_tree
  43                 .prefix
  44                 .segments
  45                 .last()
  46                 .expect("use paths cannot be empty")
  47                 .ident;
  48             unsafe_to_safe_check(old_name, new_name, cx, span);
  49         },
  50         UseTreeKind::Simple(None, ..) | UseTreeKind::Glob => {},
  51         UseTreeKind::Nested(ref nested_use_tree) => {
  52             for &(ref use_tree, _) in nested_use_tree {
  53                 check_use_tree(use_tree, cx, span);
  54             }
  55         },
  56     }
  57 }
  58
  59 fn unsafe_to_safe_check(old_name: Ident, new_name: Ident, cx: &EarlyContext<'_>, span: Span) {
  60     let old_str = old_name.name.as_str();
  61     let new_str = new_name.name.as_str();
  62     if contains_unsafe(&old_str) && !contains_unsafe(&new_str) {
  63         span_lint(
  64             cx,
  65             UNSAFE_REMOVED_FROM_NAME,
  66             span,
  67             &format!(
  68                 "removed `unsafe` from the name of `{}` in use as `{}`",
  69                 old_str, new_str
  70             ),
  71         );
  72     }
  73 }
  74
  75 #[must_use]
  76 fn contains_unsafe(name: &str) -> bool {
  77     name.contains("Unsafe") || name.contains("unsafe")
  78 }